In the above mentioned Carlson U.S. Pat. No. 3,397,490, there is described an improved arrangement for providing a pneumatically inflatable seal for door, hatches and similar closures. A seal of the general type shown and described has found advantageous use in connection with sliding door seals for modern railroad passenger cars. Railroad passenger cars, such as typically used on commuter railrods for example, frequently are designed with modern, aerodynamic shaping and are provided with relatively large access doors for rapid boarding and discharge of passengers. Sliding doors are particularly useful for such an application. Because these cars are designed for travel at relatively high speeds, effective sealing of the closed door is important, and pneumatically inflatable seals of the general type shown in the beforementioned Carlson patent have been used to advantage for this purpose.
In the construction of known inflatable seals, it is conventional to extrude a tubular body of elastomeric material, which is cut to appropriate length. This tubular body is closed at both ends by means of a solid plug of compatible material, which also mounts the necessary hardware for inflating and deflating the seal when desired.
Because of the physical limitations of the door construction in a typical passenger railroad vehicle of the type contemplated, the necessary presence in the inflatable tube of solid plug end sections requires short transition areas at the end extremities of the sealing elements that do not fully expand when the seal is inflated. Typically this transition area is located at the lower corners of a door frame, and this condition can result in a seal which is only partially effective in that transition area.
It is an objective of the invention to provide an improved, inflatable door seal, for the type of utilization contemplated above, in which the inflatable seal is provided in the area of the necessary solid plug enclosure, with special transition sealing means which, notwithstanding limited inflation of the plug end area, provides for fully effective sealing of a sliding door closure.
For a better understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of a preferred embodiment and to the accompanying drawings.